The work aims to prepare composite antibacterial film with biodegradable material as film-forming substrate added with natural antibacterial substances to study its properties, so as to keep pork fresh. First of all, the composite antibacterial membrane was prepared by tape casting with polycaprolactone (PCL) and polyvinyl alcohol (PVA) which contained nisin. Then, its effects on the optical properties, mechanical properties and antibacterial properties of the composite films were studied by changing the content of nisin. The best preservation effect of composite film with nisin content of 0.7 g was obtained, which could significantly inhibit the growth of staphylococcus aureus. After 7 days of storage, the pH value was 6.8, and the preservation time was 2 times of the blank group. The transmittance of the film was 86.13 %, and the tensile strength was 23.30 MPa. Therefore, the composite antibacterial film with nisin content of 0.7 g has the best comprehensive performance. The film has good antibacterial, optical and mechanical properties, which can prolong the fresh-keeping time of pork, and has certain guiding significance for study of functional packaging film.